Efficacy of hot water treatment for postharvest control of western flower thrips, Frankliniella occidentalis, in French beans

Background: The western flower thrips, Frankliniella occidentalis, is a quarantine pest of French beans that requires phytosanitary treatment to meet quarantine requirements for strict lucrative markets. In this study, the efficacy of hot water treatment against F. occidentalis eggs and its effects on the postharvest physicochemical quality parameters of French beans was evaluated. Results: The immersion time of 8.01 min (95% critical limits CL 7.77–8.24) was predicted by the probit model as the minimum time required to achieve a 99.9968% control level. Confirmatory tests with a large number of F. occidentalis eggs were performed to validate the estimated time to achieve probit-9 control level, and there were no survivors from the 50 103 eggs treated. Likewise, none of the 55 364 eggs exposed to 45 ± 0.2 °C for 7 min (observational time) survived. The effect of the treatment schedule on French beans quality parameters was assessed and there were no differences in weight loss, moisture content, total soluble solids, titratable acidity, pH, and reducing sugars between treated and untreated samples. Conclusion: Our results indicate that hot water treatment (at 45 ± 0.2 °C for a duration of 8.01 min is an effective phytosanitary treatment for the control of Frankliniella occidentalis on French beans, with no significant impact on pods quality. © 2022 Society of Chemical Industry

Hot Water Treatment for Post-Harvest Disinfestation of Bactrocera dorsalis (Diptera: Tephritidae) and Its Effect on cv. Tommy Atkins Mango

Mango production and trade in sub-Saharan Africa is hampered by direct damage and the high quarantine status of B. dorsalis and the paucity of effective post-harvest phytosanitary treatments. The current study reports the development of a quarantine treatment protocol using hot water to disinfest B. dorsalis and assess its effect on cv. Tommy Atkins mango quality. We first determined the development of the eggs and all larval stages of B. dorsalis in cv. Tommy Atkins mango and used the information to establish a time–mortality relationship of the immature stages after subjecting infested fruits to a regimen of eight, time instances of hot water at 46.1◦ C. Using probit analysis, we estimated the minimum time required to achieve 99.9968% mortality of each stage. Our results indicate that the egg was the least heat tolerant, followed by the first, second, and third instar. The time required to achieve 99.9968% control of the third instar in cv. Tommy Atkins mango (400–600 g) was determined to be 72.63 min (95% Cl: 70.32–74.95). In the confirmatory trials, the hot water treatment schedule of 46.1◦ C/72.63 min was validated, and none of the 59,120 most heat-tolerant individuals treated survived. Further, there were no significant differences between hot water-treated and untreated mangoes recorded in weight loss, fruit firmness, pH, total soluble solids, moisture content, and titratable acidity eleven days post-treatment. These findings demonstrate an effectively optimum post-harvest disinfestation treatment against B. dorsalis in cv. Tommy Atkins mango that should be adopted commercially to facilitate access to profitable but strict export markets globally

Advances in Postharvest Disinfestation of Fruits and Vegetables Using Hot Water Treatment Technology-Updates from Africa

Hot Water Treatment (HWT) provides adequate phytosanitary assurance that treated fruits and vegetables exported abroad are free from devastating quarantine pests. Two systems for HWT are currently available for commercial use namely the batch/jacuzzi and the continuous flow system depending on user requirements. Several protocols have been developed the world over and a few in Africa, but adoption has been lagging because of various factors chief among them lack of large scale validations of experiments to guide application at the commercial level. Mango, Bell pepper, avocado, and French beans play an important role in the livelihoods of people in Africa. However, their export is constrained by pests such as the invasive Oriental fruit fly, the false codling moth, and thrips. To circumvent this issue, disinfestation HWT protocols have been developed which seek to provide quarantine assurance to lucrative export markets. Hot Water Treatment technology has several advantages over other conventional phytosanitary treatments. It provides a triple function of cleaning, disinfesting, and disinfecting and is friendly to users, consumers of the treated commodities, and the environment. We discuss HWT in the context of its future and applicability in Africa. It is the future of postharvest treatments

Hot Water Disinfestation Treatment Does Not Affect Physical and Biochemical Properties of Export Quality Mango Fruit [Mangifera indica L.]

There are various postharvest treatments currently available in the market. Among these, heat-based treatments are very effective. Several hot water treatment (HWT) protocols at various temperature regimes and time durations have been developed for different mango cultivars and varieties. However, many concerns have been raised regarding the quality of fruits subjected to HWT, particularly on physical and biochemical properties. The purpose of this study was to generate empirical evidence on the effect of the HWT protocol currently recognized and accepted by the EU for Apple mango cultivar from Africa. We subjected mango to HWT at 46.1 °C for 68, 75, and 84 min and evaluated various physical and biochemical properties at 1, 3, 5, and 7 days post-treatment. Conventional methods of analysis were used to test acidity, antioxidants, minerals, nutrients, and physical properties of treated mangoes, and comparisons against untreated controls were made. We found no significant differences in pH, various acid content, total carotenoids, β-carotene content, vitamin A, aromatic volatiles, total phenolics, total antioxidant activity, various minerals, electrolytic leakage, crude protein, total carbohydrates, total sugars, crude fat, moisture content, dry matter, total soluble solids, firmness, or weight between treated and untreated mangoes. We conclude that HWT presents a viable alternative for postharvest treatment of export mangoes provided that quality attributes are maintained from preharvest, harvesting, transportation, treatment, and post-treatment handling

Hot Water Disinfestation Treatment Does Not Affect Physical and Biochemical Properties of Export Quality Mango Fruit [<i>Mangifera indica</i> L.]

There are various postharvest treatments currently available in the market. Among these, heat-based treatments are very effective. Several hot water treatment (HWT) protocols at various temperature regimes and time durations have been developed for different mango cultivars and varieties. However, many concerns have been raised regarding the quality of fruits subjected to HWT, particularly on physical and biochemical properties. The purpose of this study was to generate empirical evidence on the effect of the HWT protocol currently recognized and accepted by the EU for Apple mango cultivar from Africa. We subjected mango to HWT at 46.1 °C for 68, 75, and 84 min and evaluated various physical and biochemical properties at 1, 3, 5, and 7 days post-treatment. Conventional methods of analysis were used to test acidity, antioxidants, minerals, nutrients, and physical properties of treated mangoes, and comparisons against untreated controls were made. We found no significant differences in pH, various acid content, total carotenoids, β-carotene content, vitamin A, aromatic volatiles, total phenolics, total antioxidant activity, various minerals, electrolytic leakage, crude protein, total carbohydrates, total sugars, crude fat, moisture content, dry matter, total soluble solids, firmness, or weight between treated and untreated mangoes. We conclude that HWT presents a viable alternative for postharvest treatment of export mangoes provided that quality attributes are maintained from preharvest, harvesting, transportation, treatment, and post-treatment handling